Conventional soil tests, culture-based microbial methods, and the novel method of 15N-DNA stable isotope probing (SIP) were employed to illustrate atrazine biodegradation as related to the physiochemical properties of an atrazine-exposed Cisne soil. This soil exhibited enhanced atrazine degradation. Mineralization underestimated the rate of atrazine dissipation demonstrated by the accumulation of several metabolites. The soil showed high ambient concentrations of NO3-; however, NO3- did not suppress atrazine degradation. Atrazine natural attenuation was limited by incomplete distribution through the unsaturated soil matrix. Direct plating experiments from the Cisne soil isolated an atrazine-degrading microorganism, ES-1. Analysis of the 16S rRNA gene sequences from the isolate confirmed that ES-1 is closely related (99%) to Arthrobacter sp. In pure culture, the isolate rapidly converted atrazine to cyanuric acid. Accumulation of this product was consistent with metabolites in the Cisne soil, suggesting that isolate ES-1 influenced in-situ remediation of atrazine. 15N- SIP experiments were conducted using 15N-ethylamino-atrazine. The results of these experiments failed to establish a causal relationship between in-situ atrazine-degradation and ES-1 enrichment; however, these results are likely due to isotopic dilution. Further experiments using 13C-ethyl/isoproylamino-atrazine may yet verify a link between ES-1 and the enhanced natural attenuation exhibited in the Cisne soil.
Shaffer, Elizabeth; Pirnie, Malcolm; Sims, Gerald; Chee-Sanford, Joanne; Cupples, Alison M.; and Smyth, Charles
"Atrazine Biodegradation As Related To The Physiochemical Properties Of A Cisne Soil From A Major Atrazine Spill Site: Atrazine Biodegradation In A Cisne Soil Exposed To A Major Spill,"
Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy:
Vol. 13, Article 28.
Available at: http://scholarworks.umass.edu/soilsproceedings/vol13/iss1/28